[apple/xnu.git] / osfmk / kern / kext_alloc.c

/*
 * Copyright (c) 2008 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
#include <kern/assert.h>
#include <kern/debug.h>
#include <kern/kext_alloc.h>
#include <kern/misc_protos.h>

#include <mach/host_priv_server.h>
#include <mach/kern_return.h>
#include <mach/mach_vm.h>
#include <mach/vm_map.h>
#include <mach/vm_types.h>

#include <mach-o/loader.h>
#include <libkern/kernel_mach_header.h>

#define KASLR_IOREG_DEBUG 0


vm_map_t g_kext_map = 0;
#if KASLR_IOREG_DEBUG
mach_vm_offset_t kext_alloc_base = 0;
mach_vm_offset_t kext_alloc_max = 0;
#else
static mach_vm_offset_t kext_alloc_base = 0;
static mach_vm_offset_t kext_alloc_max = 0;
#if CONFIG_KEXT_BASEMENT
static mach_vm_offset_t kext_post_boot_base = 0;
#endif
#endif

/*
 * On x86_64 systems, kernel extension text must remain within 2GB of the
 * kernel's text segment.  To ensure this happens, we snag 2GB of kernel VM
 * as early as possible for kext allocations.
 */
void 
kext_alloc_init(void)
{
#if CONFIG_KEXT_BASEMENT
    kern_return_t rval = 0;
    kernel_segment_command_t *text = NULL;
    kernel_segment_command_t *prelinkTextSegment = NULL;
    mach_vm_offset_t text_end, text_start;
    mach_vm_size_t text_size;
    mach_vm_size_t kext_alloc_size;

    /* Determine the start of the kernel's __TEXT segment and determine the
     * lower bound of the allocated submap for kext allocations.
     */

    text = getsegbyname(SEG_TEXT);
    text_start = vm_map_trunc_page(text->vmaddr,
				   VM_MAP_PAGE_MASK(kernel_map));
    text_start &= ~((512ULL * 1024 * 1024 * 1024) - 1);
    text_end = vm_map_round_page(text->vmaddr + text->vmsize,
				 VM_MAP_PAGE_MASK(kernel_map));
    text_size = text_end - text_start;

    kext_alloc_base = KEXT_ALLOC_BASE(text_end);
    kext_alloc_size = KEXT_ALLOC_SIZE(text_size);
    kext_alloc_max = kext_alloc_base + kext_alloc_size;
    
    /* Post boot kext allocation will start after the prelinked kexts */
    prelinkTextSegment = getsegbyname("__PRELINK_TEXT");
    if (prelinkTextSegment) {
        /* use kext_post_boot_base to start allocations past all the prelinked 
         * kexts
         */
        kext_post_boot_base = 
		vm_map_round_page(kext_alloc_base + prelinkTextSegment->vmsize,
				  VM_MAP_PAGE_MASK(kernel_map));
    }
    else {
        kext_post_boot_base = kext_alloc_base;
    }

    /* Allocate the sub block of the kernel map */
    rval = kmem_suballoc(kernel_map, (vm_offset_t *) &kext_alloc_base, 
			 kext_alloc_size, /* pageable */ TRUE,
			 VM_FLAGS_FIXED|VM_FLAGS_OVERWRITE,
			 &g_kext_map);
    if (rval != KERN_SUCCESS) {
	    panic("kext_alloc_init: kmem_suballoc failed 0x%x\n", rval);
    }

    if ((kext_alloc_base + kext_alloc_size) > kext_alloc_max) {
        panic("kext_alloc_init: failed to get first 2GB\n");
    }

    if (kernel_map->min_offset > kext_alloc_base) {
	    kernel_map->min_offset = kext_alloc_base;
    }

    printf("kext submap [0x%lx - 0x%lx], kernel text [0x%lx - 0x%lx]\n",
	   VM_KERNEL_UNSLIDE(kext_alloc_base),
	   VM_KERNEL_UNSLIDE(kext_alloc_max),
	   VM_KERNEL_UNSLIDE(text->vmaddr),
	   VM_KERNEL_UNSLIDE(text->vmaddr + text->vmsize));

#else
    g_kext_map = kernel_map;
    kext_alloc_base = VM_MIN_KERNEL_ADDRESS;
    kext_alloc_max = VM_MAX_KERNEL_ADDRESS;
#endif /* CONFIG_KEXT_BASEMENT */
}

kern_return_t
kext_alloc(vm_offset_t *_addr, vm_size_t size, boolean_t fixed)
{
    kern_return_t rval = 0;
#if CONFIG_KEXT_BASEMENT
    mach_vm_offset_t addr = (fixed) ? *_addr : kext_post_boot_base;
#else
    mach_vm_offset_t addr = (fixed) ? *_addr : kext_alloc_base;
#endif
    int flags = (fixed) ? VM_FLAGS_FIXED : VM_FLAGS_ANYWHERE;
 
#if CONFIG_KEXT_BASEMENT
    /* Allocate the kext virtual memory
     * 10608884 - use mach_vm_map since we want VM_FLAGS_ANYWHERE allocated past
     * kext_post_boot_base (when possible).  mach_vm_allocate will always 
     * start at 0 into the map no matter what you pass in addr.  We want non 
     * fixed (post boot) kext allocations to start looking for free space 
     * just past where prelinked kexts have loaded.  
     */
    rval = mach_vm_map(g_kext_map, 
                       &addr, 
                       size, 
                       0,
                       flags,
                       MACH_PORT_NULL,
                       0,
                       TRUE,
                       VM_PROT_DEFAULT,
                       VM_PROT_ALL,
                       VM_INHERIT_DEFAULT);
    if (rval != KERN_SUCCESS) {
        printf("mach_vm_map failed - %d\n", rval);
        goto finish;
    }
#else
    rval = mach_vm_allocate(g_kext_map, &addr, size, flags);
    if (rval != KERN_SUCCESS) {
        printf("vm_allocate failed - %d\n", rval);
        goto finish;
    }
#endif

    /* Check that the memory is reachable by kernel text */
    if ((addr + size) > kext_alloc_max) {
        kext_free((vm_offset_t)addr, size);
        rval = KERN_INVALID_ADDRESS;
        goto finish;
    }

    *_addr = (vm_offset_t)addr;
    rval = KERN_SUCCESS;

finish:
    return rval;
}

void 
kext_free(vm_offset_t addr, vm_size_t size)
{
    kern_return_t rval;

    rval = mach_vm_deallocate(g_kext_map, addr, size);
    assert(rval == KERN_SUCCESS);
}
Commit	Line	Data
b0d623f7 A	1	/*
	2	* Copyright (c) 2008 Apple Inc. All rights reserved.
	3	*
	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
	5	*
	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
	14	*
	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
	25	*
	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
	27	*/
	28	#include <kern/assert.h>
	29	#include <kern/debug.h>
	30	#include <kern/kext_alloc.h>
	31	#include <kern/misc_protos.h>
	32
	33	#include <mach/host_priv_server.h>
	34	#include <mach/kern_return.h>
	35	#include <mach/mach_vm.h>
	36	#include <mach/vm_map.h>
	37	#include <mach/vm_types.h>
	38
	39	#include <mach-o/loader.h>
	40	#include <libkern/kernel_mach_header.h>
	41
316670eb A	42	#define KASLR_IOREG_DEBUG 0
316670eb A	43
b0d623f7 A	44
b0d623f7 A	45	vm_map_t g_kext_map = 0;
316670eb A	46	#if KASLR_IOREG_DEBUG
	47	mach_vm_offset_t kext_alloc_base = 0;
	48	mach_vm_offset_t kext_alloc_max = 0;
	49	#else
b0d623f7 A	50	static mach_vm_offset_t kext_alloc_base = 0;
b0d623f7 A	51	static mach_vm_offset_t kext_alloc_max = 0;
316670eb A	52	#if CONFIG_KEXT_BASEMENT
	53	static mach_vm_offset_t kext_post_boot_base = 0;
	54	#endif
	55	#endif
b0d623f7 A	56
	57	/*
	58	* On x86_64 systems, kernel extension text must remain within 2GB of the
	59	* kernel's text segment. To ensure this happens, we snag 2GB of kernel VM
	60	* as early as possible for kext allocations.
	61	*/
	62	void
	63	kext_alloc_init(void)
	64	{
316670eb	65	#if CONFIG_KEXT_BASEMENT
b0d623f7 A	66	kern_return_t rval = 0;
b0d623f7 A	67	kernel_segment_command_t *text = NULL;
316670eb	68	kernel_segment_command_t *prelinkTextSegment = NULL;
b0d623f7 A	69	mach_vm_offset_t text_end, text_start;
	70	mach_vm_size_t text_size;
	71	mach_vm_size_t kext_alloc_size;
	72
	73	/* Determine the start of the kernel's __TEXT segment and determine the
	74	* lower bound of the allocated submap for kext allocations.
	75	*/
	76
	77	text = getsegbyname(SEG_TEXT);
39236c6e A	78	text_start = vm_map_trunc_page(text->vmaddr,
39236c6e A	79	VM_MAP_PAGE_MASK(kernel_map));
b0d623f7	80	text_start &= ~((512ULL * 1024 * 1024 * 1024) - 1);
39236c6e A	81	text_end = vm_map_round_page(text->vmaddr + text->vmsize,
39236c6e A	82	VM_MAP_PAGE_MASK(kernel_map));
b0d623f7 A	83	text_size = text_end - text_start;
b0d623f7 A	84
6d2010ae A	85	kext_alloc_base = KEXT_ALLOC_BASE(text_end);
6d2010ae A	86	kext_alloc_size = KEXT_ALLOC_SIZE(text_size);
b0d623f7	87	kext_alloc_max = kext_alloc_base + kext_alloc_size;
316670eb A	88
	89	/* Post boot kext allocation will start after the prelinked kexts */
	90	prelinkTextSegment = getsegbyname("__PRELINK_TEXT");
	91	if (prelinkTextSegment) {
	92	/* use kext_post_boot_base to start allocations past all the prelinked
	93	* kexts
	94	*/
	95	kext_post_boot_base =
39236c6e A	96	vm_map_round_page(kext_alloc_base + prelinkTextSegment->vmsize,
39236c6e A	97	VM_MAP_PAGE_MASK(kernel_map));
316670eb A	98	}
	99	else {
	100	kext_post_boot_base = kext_alloc_base;
	101	}
b0d623f7	102
316670eb	103	/* Allocate the sub block of the kernel map */
b0d623f7 A	104	rval = kmem_suballoc(kernel_map, (vm_offset_t *) &kext_alloc_base,
b0d623f7 A	105	kext_alloc_size, /* pageable */ TRUE,
6d2010ae	106	VM_FLAGS_FIXED\|VM_FLAGS_OVERWRITE,
b0d623f7 A	107	&g_kext_map);
	108	if (rval != KERN_SUCCESS) {
	109	panic("kext_alloc_init: kmem_suballoc failed 0x%x\n", rval);
	110	}
	111
	112	if ((kext_alloc_base + kext_alloc_size) > kext_alloc_max) {
	113	panic("kext_alloc_init: failed to get first 2GB\n");
	114	}
	115
	116	if (kernel_map->min_offset > kext_alloc_base) {
	117	kernel_map->min_offset = kext_alloc_base;
	118	}
	119
316670eb A	120	printf("kext submap [0x%lx - 0x%lx], kernel text [0x%lx - 0x%lx]\n",
	121	VM_KERNEL_UNSLIDE(kext_alloc_base),
	122	VM_KERNEL_UNSLIDE(kext_alloc_max),
	123	VM_KERNEL_UNSLIDE(text->vmaddr),
	124	VM_KERNEL_UNSLIDE(text->vmaddr + text->vmsize));
	125
b0d623f7 A	126	#else
	127	g_kext_map = kernel_map;
	128	kext_alloc_base = VM_MIN_KERNEL_ADDRESS;
	129	kext_alloc_max = VM_MAX_KERNEL_ADDRESS;
316670eb	130	#endif /* CONFIG_KEXT_BASEMENT */
b0d623f7 A	131	}
	132
	133	kern_return_t
	134	kext_alloc(vm_offset_t *_addr, vm_size_t size, boolean_t fixed)
	135	{
	136	kern_return_t rval = 0;
316670eb A	137	#if CONFIG_KEXT_BASEMENT
	138	mach_vm_offset_t addr = (fixed) ? *_addr : kext_post_boot_base;
	139	#else
b0d623f7	140	mach_vm_offset_t addr = (fixed) ? *_addr : kext_alloc_base;
316670eb	141	#endif
b0d623f7 A	142	int flags = (fixed) ? VM_FLAGS_FIXED : VM_FLAGS_ANYWHERE;
b0d623f7 A	143
316670eb A	144	#if CONFIG_KEXT_BASEMENT
	145	/* Allocate the kext virtual memory
	146	* 10608884 - use mach_vm_map since we want VM_FLAGS_ANYWHERE allocated past
	147	* kext_post_boot_base (when possible). mach_vm_allocate will always
	148	* start at 0 into the map no matter what you pass in addr. We want non
	149	* fixed (post boot) kext allocations to start looking for free space
	150	* just past where prelinked kexts have loaded.
	151	*/
	152	rval = mach_vm_map(g_kext_map,
	153	&addr,
	154	size,
	155	0,
	156	flags,
	157	MACH_PORT_NULL,
	158	0,
	159	TRUE,
	160	VM_PROT_DEFAULT,
	161	VM_PROT_ALL,
	162	VM_INHERIT_DEFAULT);
	163	if (rval != KERN_SUCCESS) {
	164	printf("mach_vm_map failed - %d\n", rval);
	165	goto finish;
	166	}
	167	#else
b0d623f7 A	168	rval = mach_vm_allocate(g_kext_map, &addr, size, flags);
	169	if (rval != KERN_SUCCESS) {
	170	printf("vm_allocate failed - %d\n", rval);
	171	goto finish;
	172	}
316670eb	173	#endif
b0d623f7 A	174
	175	/* Check that the memory is reachable by kernel text */
	176	if ((addr + size) > kext_alloc_max) {
	177	kext_free((vm_offset_t)addr, size);
316670eb	178	rval = KERN_INVALID_ADDRESS;
b0d623f7 A	179	goto finish;
	180	}
	181
	182	*_addr = (vm_offset_t)addr;
	183	rval = KERN_SUCCESS;
	184
	185	finish:
	186	return rval;
	187	}
	188
	189	void
	190	kext_free(vm_offset_t addr, vm_size_t size)
	191	{
	192	kern_return_t rval;
	193
	194	rval = mach_vm_deallocate(g_kext_map, addr, size);
	195	assert(rval == KERN_SUCCESS);
	196	}
	197